The invention relates to a modular system comprising various component modules for the production of coating compositions for coating plastics and to a process for the production of coating compositions using this modular system. The modular system and the process may be used in vehicle and industrial coating, in particular in vehicle repair coating.
In vehicle construction, in addition to the usual metals, increased use is also being made of plastics for various vehicle parts and attachments, such as for example external mirror casings, bumpers, spoilers, trim strips etc. The plastics used are, for example, polyolefins, such as polypropylene, polystyrene, polycarbonate, ABS (acrylonitrile/butadiene/styrene copolymers), polyamide, polymer blends prepared from the stated plastics and glass fibre reinforced plastics. However, when coating plastics parts, problems with adhesion to the substrate occur to a greater or lesser degree depending upon the plastic used. Non-polar plastics, such as for example polypropylene, require adhesion-promoting pretreatment and/or specially developed adhesion primers in order to be coatable at all.
In order to achieve optimum adhesion results on various plastics substrates, adhesion-promoting coating compositions, known as adhesion primers, tailored to the particular plastic have been developed and these are applied as the first layer on the plastics surface where they are intended to ensure adhesion of the complete coating structure to the plastic. So that the product range required for this purpose may be limited in size on economic grounds, the industry has already changed over to developing xe2x80x9cgeneral purposexe2x80x9d products which achieve at least adequate adhesion on all plastics substrates which may, in principle, be coated.
Such general purpose adhesion primers are described, for example, in DE-A-44 05 148 (U.S. Pat. No. 5,523,336). The adhesion primers described in said document are waterborne coating compositions and contain water-dilutable self-emulsifying epoxy resins and chlorinated polyolefins.
However, the generally satisfactory overall level of properties achievable with these general purpose products does not always adequately meet the specifications placed upon coating products, for example by automotive manufacturers.
In particular in vehicle coating and vehicle repair coating, there is accordingly a need for coating compositions for coating plastics, which compositions on the one hand exhibit good, general purpose adhesion to the various plastics substrates and simultaneously meet the automotive industry""s specifications with regard to the overall range of properties. The coating compositions should thus achieve good to very good results in a series of specific tests, such as the condensed water test, breakdown test, stone impact test, steam jet test, crosscut test, alternating temperature test.
The present invention provides a modular system comprising individual constituent modules, which system, by the combination of various module units, permits the production of coating compositions with good adhesion which meet the particular requirements placed upon them and thus satisfies the above-stated need.
The invention relates to a modular system for the production of coating compositions for coating plastics comprising the following component modules:
A) at least one base module containing at least one binder, extenders and/or pigments, optionally together with conventional coating additives, water and/or organic solvents,
B) at least one adhesion module containing at least one adhesion-promoting component optionally together with binders, conventional coating additives, extenders, organic solvents and/or water,
C) at least one elasticity module containing at least one elasticising component optionally together with conventional coating additives, extenders, organic solvents and/or water and
D) at least one binder module containing at least one binder optionally together with additives, organic solvents and/or water.